Short Info about Heat treatment

as a part of this group I (Haroon) have to do heat treatment test on samples, which are going to be provieded to us. since the samples are not ready i will write abut the process and procedure of the waork later on. but beofre doing all those testings its better to know what heat treatment it self is?

Heat Treatment is the controlled heating and cooling of metals to change their physical and mechanical properties without changing the product shape. Heat Treatment is often associated with increasing the strength of material, but it can also be used to change certain manufacturability objectives such as improve machining, improve formability, restore ductility after a cold working operation. Thus it is a very enabling manufacturing process that can not only help other manufacturing process, but can also improve product performance by increasing strength or other desirable characteristics. Steels and alloys are particularly suitable for heat treatment, since they respond well to heat treatment and the commercial use of steels exceeds that of any other material. Metallic materials consist of a microstructure of small crystals called "grains" or crystallites. The nature of the grains (i.e. grain size and composition) determine the overall mechanical behavior of the metal. Heat treatment provides an efficient way to manipulate the properties of the metal by controlling rate of diffusion, and the rate of cooling within the microstructure. In carbon and low alloy steels, fast rates of cooling result in a high degree of hardness. The idea of heat treating a steel and alloy is to dissolve carbon onto the crystal structure and then retain this structure down to room temperature. This is happening only if the alloys have enough carbon. After the steels or alloys are heated, they are cooled in water in order the keep their structure and it’s done in room temperature. This process is called quenching. Quenched Steel and alloy are harder than those which are annealed.